"Alien" (1979, Ridley Scott): A horror/science fiction masterwork in which a creature that emerges from John Hurt's stomach hides inside a spaceship, grows to gargantuan size and begins killing off crew members. It's up to Ripley (Sigourney Weaver) to fight the thing. Distinct in many departments, the film featured bona-fide scary violence, a strong female heroine, working-class heroes over scientists, effective use of claustrophobia and the design work of H.R. Giger. Highly inventive. (KM)

"Blade Runner" (1982, Ridley Scott): This adaptation of a Philip K. Dick novel is a satisfying blend of science fiction, private eye yarn and religious allegory set in a world even more dazzling and influential than the one Scott contrived for "Alien." There have been several editions -- including more than one director's cut -- but for those dazzled by the original, it's only truly "Blade Runner" if it's got Harrison Ford's Chandleresque narration. (SL)

"The Day the Earth Stood Still" (1951, Robert Wise): An allegory of humanity confronting its relative puniness, both internal and external, it stands the test of time as a smart, lucid futuristic thriller of the Ray Bradbury/Isaac Asimov stripe. Read this film as a religious parable, a political warning, a dissection of human fear and loathing or as a simple aliens-are-among us chiller and it's still a classic. (SL)

"Metropolis" (1927, Fritz Lang): Lang's monumental silent film has been butchered, restored and re-released so many times that there is no definitive version. But this futuristic fable of underclass revolt has a look so revolutionary that you see echoes of it in such films as "The Fifth Element" and, especially, "Blade Runner." (GB)

"The Empire Strikes Back" (1980, Irvin Kershner): It is your destiny! This dark heart of the original "Star Wars" trilogy riveted audiences when it was first released with its great plot twist: Luke Skywalker learns that evil Darth Vader turns out to be dear ol' dad. But it's the introduction of two key characters -- Jedi master Yoda and bounty hunter Boba Fett -- and those incredible snow walkers that gives this sequel an edge on the original. (GB)

"Star Wars" (1977, George Lucas): "A long time ago in a galaxy far, far away" is the opening premise. Then comes John Williams' blast of brass and the opening story crawl that changed sci-fi forever. The story evokes the film serials of the 1940s and '50s, and none of the acting rises above that level -- even thespian Alec Guinness overdoes it a bit. But the story of how farm boy Luke Skywalker becomes an intergalactic hero is the stuff of myth, echoing Shakespeare, Wagner and Jung. Heady stuff for a movie in which one of the leads has a cinnamon-bun hairdo. (GB)

"The Matrix" (1999, Andy and Larry Wachowski): When this film first arrived, viewers were shocked -- a movie starring Keanu Reeves was actually, very, very good! Influential, exciting action and fight choreography has been copied countless times (the slow bullet, the computer-style fighting, that back bend) and the film's story just gets more complicated through each sequel. But so far, the first one is still the best. (KM)

"Close Encounters of the Third Kind" (1977, Steven Spielberg): Perhaps the finest distillation of Spielberg's career-long obsession with restless, absent fathers and the possibility of reconciliation through a supernatural outside agency. There's an epic sweep to it and a satisfying payoff -- though some of us prefer the leaner finale of the original to the effects-rich Special Edition. (SL)

"2001: A Space Odyssey" (1968, Stanley Kubrick): A conversation about "2001" can last a moment or a month. At once demanding and defying explication, Kubrick's airy masterpiece frustrated audiences on its initial release. But its legend has steadily (and rightfully) grown to meet its tremendous, near-stifling ambition. It's science fiction stripped to its skeletal ideals. If you're in the right mood, it exercises the imagination like nothing else. (NR)

"E.T. the Extra-Terrestrial" (1982, Steven Spielberg): What makes "E.T." one of the best sci-fi films of all time and one of the most popular is that it's not "science fiction" per se. By the time ET's intergalactic cell phone summons the mother ship and he goes scurrying up that ramp, we know what Elliot is feeling. Maybe we've never been on a moonlit bike ride with an alien, but we've all had friends move away. (NR)

"Terminator 2" (1991, James Cameron): The kinder, gentler Terminator, with the title robot (and Gov.-elect Arnold Schwarzenegger) programmed to protect a boy whose future lies in leading the resistance against hostile machines. Meanwhile, that boy's mother, (Linda Hamilton) has developed a seriously buff body and deep-seated, almost irrational rage. Glorious, expensive special effects mark this explosive ride, including a horrifying nuclear holocaust. Not surprisingly, director Cameron moved on to romance with "Titanic." (KM)

"Alphaville" (1965, Jean-Luc Godard): You never expect the norm from Godard, and you don't get it here. A combination of science fiction and detective noir decades before "Blade Runner," it's steeped in abstruse philosophy, French existentialist cool and the director's patented jumps, leaps, sidles and logical obscurities. And it's fascinating, funny and haunting. (If you've never seen it and it looks familiar, you've probably seen the Cranberries' video for "Linger," which lovingly rips it off.) (SL)

"Aliens" (1986, James Cameron): It's hard to top Ridley Scott's original, but Cameron's follow-up comes close. Instead of the foreboding horror of "Alien," this one's got action aplenty, as Ellen Ripley comes out of hibernation after decades and returns to battle the beasties with a squad of space marines and a little girl named Newt. The extended cut includes even more window-rattling mayhem. (MM)

"A Clockwork Orange" (1971, Stanley Kubrick): Whether or not it's stood the test of time and proved itself as prophetic as some other sci-fi, there's no denying the impact Kubrick's darkest work undeniably still carries. If Alex and his droogs sipping milk and carousing in the film's cathartic first 20 minutes doesn't stick with you for the rest of your life, you are immune to the unique powers of cinema. (NR)

"Brazil" (1985, Terry Gilliam): A dystopian future in all its surreal, frightening, frustrating and maddening glory, "Brazil" is Gilliam's masterpiece. Jonathan Pryce is a Walter Mitty/Franz Kafka character who's a hero in his dream life but a meek man in the waking world, fearful of totalitarianism. More happens, but it would take too long to explain. Just watch and re-watch. (KM)

"Mad Max 2: The Road Warrior" (1981, George Miller): It may be sci-fi without the "sci," but this all-out, nonstop actioner about a postapocalyptic showdown between fuel-hoarding ninnies and tough-guys in gay fetish gear made Mel Gibson's career. There's almost no dialogue, and to pick up the "plot" you'll have to see the first film, but man -- those last 30 minutes are like chewing on a human adrenal gland. (NR)

"The Thing From Another World" (1951, Christian Nyby): Maybe the best sci-fi film of the 1950s, this chiller has a group of Arctic Circle scientists investigating a crashed saucer and finding a frozen alien, which then thaws and . . . well, the story may be predictable, but it's masterfully carried off. Howard Hawks was credited only as producer, but his directorial fingerprints are all over the film. (MM)

"Solaris" (1972, Anrdei Tarkovsky): This cerebral sci-fi fable was the great Russian director's answer to "2001." It follows a psychologist sent to investigate the goings-on at a space station that's orbiting an intelligent planet that brings to life the dreams of nearby humans (the psychologist, for one, sees his long-dead wife). This thinking fan's alternative to interstellar dogfights was remade with some success by Steven Soderbergh in 2002. (MM)

"Invasion of the Body Snatchers" (1956, Don Siegel): A classic B-movie that functions just fine as a cheap thriller but resonates more deeply as an allegory of political and cultural conformity and intolerance. The story of normal people being taken over by pod monsters from outer space is a perfect instance of the way in which science-fiction films were used by Hollywood free-thinkers as a way to critique their contemporary society without making their bosses too suspicious. (SL)

"The Terminator" (1984, James Cameron): The key to this movie's success is its broad appeal. It's a fright, a warning, a smirk. But look beyond the rush of the seat-gripping chases, the shock of the cyborg's relentless killer instinct, all the memorable one-liners. At its heart, it's a love story. And that uniquely human tale of love in the time of chaos propels us to see past director Cameron's dated '80s setting, herky-jerky robot special effects and brutal violence. (SV)

"Testuo: The Iron Man" (1988, Shinya Tsukamoto): This short but intense black-and-white feature embodies the ultimate cyberpunk nightmare. A Japanese man is involved in a hit-and-run accident and then discovers metal bits are beginning to protrude from his body. Low on dialogue and story but off the charts in the weirdness department: fundamental cyberpunk. There's a sequel if you're up for it. (MM)

"Things to Come" (1936, William Cameron Menzies): One of the best films made from an H.G. Wells novel (he wrote the script himself) and a fascinating instance of between-the-wars futurism. The stunning decor -- part Art Deco, part German Expressionist -- and the deep concern with finding rational solutions for social ills date it, but in a thrilling way. The first truly important sci-fi film of the talkie era. (SL)

"Star Trek II: The Wrath of Khan" (1982, Nicholas Meyer): The first "Star Trek" movie was so dull and ponderous that audience expectations for this follow up were lower than Lt. Uhura's plunging necklines from the original TV series. But this battle of wills between William Shatner's Kirk and Ricardo Montalban's Khan is a thrill ride, taking themes of vengeance from "Moby Dick" and "The Duellists" and casting them among the stars. (GB)

"Mad Max" (1979, George Miller): It's the Glory Riders (bikers) vs. the Bronze (the police) in this futurist tale of vengeance starring a young, fresh-faced but perfectly angry Mel Gibson. Raging against those who killed his partner, his wife and his kid, Max involves himself in all kinds of expertly filmed car chase sequences, explosions and dehumanizing violence. Bravura action direction by Miller. (KM)

"Forbidden Planet" (1956, Fred M. Wilcox): By their very definition, science-fiction films are ahead of their time. But the essential look of some of these -- including "Forbidden Planet" -- holds up better than others. Sleek Deco-inspired props and color scheme, startling special effects, eerie theremin-driven score, the drolly interactive mechanical man (Robby the Robot!), wide-screen CinemaScope presentation, Anne Francis' scanty outfits: to audiences in the '50s it all must've been future shock. Today, it remains a brilliant cinematic realization. (SV)

"Back to the Future" (1985, Robert Zemeckis): Ah, for the heyday of Spielbergian fantasy, when a well-scrubbed teenager named Marty McFly (Michael J. Fox) could ride old Doc Brown's (Christopher Lloyd) time-traveling DeLorean 30 years into the past, meeting his geeky pop (Crispin Glover) and lusty mom (Lea Thompson) and, by the way, inventing rock 'n' roll: Those were the days! (MM)

"The City of Lost Children" (1995, Marc Caro and Jean-Pierre Jeunet): This futuristic fantasy feels like a twisted mix of "Oliver Twist" and "A Clockwork Orange," with evil Santas, a wretched old dream-stealer, clones, a giant, kidnapped orphans, a bodiless brainiac and a bizarre blend of ancient and futuristic look and feel. Fittingly, it recalls Jules Verne, another Frenchman and one of the key innovators of sci-fi. (SL)

"The Incredible Shrinking Man" (1957, Jack Arnold): The quality of '50s sci-fi varied wildly -- too much of it was dedicated to attacks by ridiculous aliens. Here, though, is a campy premise taken to unthinkable heights. There are the requisite battles with spiders and housecats, but mostly the increasingly diminutive hero is introspective, turning his predicament into a treatise on the human condition. (NR)

"Them!" (1954, Gordon Douglas): In the 1950s, the Cold War at its peak, the world began understanding the deep dangers of the nuclear age, and this big-bug potboiler about mutant ants captured those fears. The claustrophobic chases through the sewers of Los Angeles influenced all monster movies that followed, including "Aliens" and "Starship Troopers." (GB)

"Akira" (1988, Katsuhiro Otomo): No movie so dominates its genre the way "Akira" does anime. To many outside the cultish fan base that Japanese animation has found here, "Akira" is anime and vice versa. The animation is typically vivid and fast-moving, and the postapocalyptic plot shadows the ideas that have influenced Japan's postwar cultural identity. (NR)

"Invasion of the Body Snatchers" (1978, Philip Kaufman): Horrifying and worthy remake of the 1956 original, Kaufman's "Snatchers" has pod people living in San Francisco with just a handful of folks aware of their presence. Amazing and sensitive acting by Donald Sutherland makes this a more emotional effort, a film where you're simultaneously frightened and near tears. The end -- and Sutherland's scream -- is harrowing. (KM)

"Fahrenheit 451" (1966, Francois Truffaut): A grown-up adaptation of Ray Bradbury's dystopic novel is about a future society where books are not only banned but systematically burned by firemen at the temperature indicated in the title. Oskar Werner is the fireman who becomes a book-memorizing rebel in Truffaut's very '60s but sturdy and handsome film. (SL)

"Repo Man" (1984, Alex Cox): Both Cox and Emilio Estevez looked destined for stardom after this, a strange and hilarious farce set in a Los Angeles not too dissimilar from today's. The fundamental weirdness is part of the charm, as teams of punk auto repossessers scavenge the city, searching for a car with aliens in its trunk. It's "Fear and Loathing" gone even more haywire. (NR)

"Planet of the Apes" (1968, Franklin J. Schaffner): The year this movie was released, the United States was at war in Vietnam and civil rights leader Martin Luther King Jr. was gunned down, and this saga echoed the tumult of the time. Charlton Heston stars as an astronaut who crashes onto a planet where the order of man and beast is turned upside down, with gorillas and chimps in charge, and humans as uncivilized animals. In the end, he learns that the monkey business is rooted in humanity's self-destructive nature. (GB)

"12 Monkeys" (1995, Terry Gilliam): Inspired by the 1962 French short "La Jetee," Gilliam adds another near masterful, bizarro entry into his dystopian arsenal. Bruce Willis is a prisoner who's sent to figure out the mysterious connection between a plague that has eradicated 99 percent of the population and a loony fanatic (played by a scene-chewing Brad Pitt). Offbeat (to say the least) and frequently depressing, the film improves and becomes more understandable with each viewing. (KM)

"20,000 Leagues Under the Sea" (1954, Richard Fleischer): Or: "Finding Nemo, Old School." The Disney live-action take on Jules Verne's seminal science-fiction novel is an epic fantasy, with spry Kirk Douglas cavorting about and James Mason as the commander of that mysterious subaquatic juggernaut, the Nautilus. The giant squid attack is a highlight, with great special effects for its time. (MM)

"Delicatessen" (1991, Marc Caro and Jean-Pierre Jeunet): The first postapocalyptic slapstick comedy about cannibalism, it's set in a future where the rarity of meat makes the residents of an apartment building turn a blind eye whenever the ground-floor butcher shop provides them with an extra tasty treat. It's "Soylent Green" meets "Hellzapopin" by the team that went on to make "Alien Resurrection." (MM)

"Fantastic Planet" (1973, Rene Laloux) Using hallucinatory animation, this arty French effort might be a parable for class struggles, with its story of a distant world where the tiny Oms fight for their freedoms from the gigantic Draags. Or it might just be a typically utopian piece of wonderful 1970s eye candy. (MM)

"The Fly" (1986, David Cronenberg): This updating of the cheesy 1958 monster movie for the age of AIDS is one of the creepiest of that master of the macabre's stylish works. As scientist Jeff Goldblum evolves more completely into the monster he calls Brundlefly, we squirm, we hide our eyes and we think long and hard about mixing technology and humanity. Essential sci-fi stuff. (SL)

"Jurassic Park" (1992, Steven Spielberg): Hidden amid the hoopla that surrounded its release, and obscured by two mediocre sequels, is a real treasure. Viewing it again, now, those first few dinosaurs -- withheld from the audience for an eternity -- may not be up to the standards of today's computer-generated effects. At the time, though, we'd never seen anything like it. Spielberg, to his credit, anticipated that awe and built on it something memorable. (NR)

"Silent Running" (1971, Douglas Trumbull): This directorial debut by special-effects guru Trumbull had a kind of inspirational effect on filmgoers. That's not just because its ecological message's time had come, but also because of the impassioned performance of star Bruce Dern, who plays an idealistic botanist adrift in an orbiting greenhouse. Not to mention his only friends, those personable waddling drones, Huey and Dewey. (SV)

"Return of the Jedi" (1983, Richard Marquand): Rumor has it that George Lucas' original concept had the planet of Endor as the wookie home world. Think of how different that ewok-free movie would have been. Still, "Jedi" has the best action sequences of the series -- the Imperial speeder bike chase through the forest and the three simultaneous sequences at the finale -- and introduces Ian McDiarmid's wicked and wonderful Emperor Palpatine. He had us at hello. (GB)

"The Brother From Another Planet" (1984, John Sayles): One of indie king Sayles' best films, it finds a likable, sweet black alien (the great Joe Morton) who's mute (and has six toes) wandering through Harlem and being chased by white alien bounty hunters. The alien settles into his new setting via his "magic touch" -- he can remarkably fix video games and television sets -- and his amiable nature draws people to him. One of the genre's most unusual entries. (KM)

"The Fifth Element" (1997, Luc Besson): Give a Frenchman the budget and scale associated with the typical Hollywood sci-fi epic and you get something like this: witty, light, gorgeous and infused with romance, with which this genre is, by and large, sorely lacking. The audacious imagination of Besson's gigantoid movie dazzles, right down to the love-conquers-all motif at the end. Stunningly beautiful and rollicking fun, even with Bruce Willis and Chris Tucker in it. (SL)

"The Thing" (1982, John Carpenter): Horror guru Carpenter fashioned this tense 'Alien'-at-the-South-Pole nightmare. Kurt Russell and company, doing research and drinking heavily in Antarctica, discover an ancient, shape-shifting alien. From the get-go, it's an impossibly tense battle, not for their own survival, which is likely forfeit, but for that of the rest of the world. (NR)

"Dark City" (1998, Alex Proyas): This visionary cross of film noir and science fiction goes beyond even "Blade Runner" in look-and-feel. A man finds himself shocked by the irrational textures and events in a gloomy city, only to learn, at some peril, that the world he lives in isn't remotely rational or even real. The contrivances and weakish central performance do nothing to diminish the imaginative power of the whole. (SL)

"Pitch Black" (2000, David Twohy): After their spaceship crash-lands on a barren world, a small band of survivors must fend off the nasty beasties that emerge when the triple-sunned planet enters a rare night. Radha Mitchell is spunky and steely as the ship's pilot, and this was one of Vin Diesel's big steps toward his 15 minutes of significance. (MM)

"The Rocky Horror Picture Show" (1975, Jim Sharman): This long-time cult musical doesn't feel like science fiction, but it's got aliens, ray guns and a spaceship, and the opening song is called "Science Fiction," so what else could it be? Including it on this list (and it is truly beloved by its adherents) is proof of how big and influential the sci-fi genre is -- not to mention that it's capable of humor and sex. (SL)

"The Man Who Fell to Earth" (1976, Nicolas Roeg): The gaunt, jaded David Bowie of the post-glam, pre-disco era is the perfect emblem of cunning, sexy boredom in this very '70s story about a space alien with altruistic intentions who winds up corrupted by the seamy reality of life on Earth. Droll and gorgeous. (SL)

"Starship Troopers" (1997, Paul Verhoeven): Vastly misunderstood sci-fi satire directed by Verhoeven ("Robocop"), this is much more than a film about killing humongous bugs on another planet. Chock-full of what Derek Zoolander would call actors who are "really, really ridiculously good-looking," this adaptation of Robert Heinlen's 1959 novel riffs on totalitarianism, propaganda and comic books. Gooey, gory hilarious fun. (KM)

And the 5 worst Sci-Fi movies ever made...

"Plan 9 From Outer Space " (1959, Edward D. Wood Jr.): There are people who will tell you that Wood's films are underrated treasures, just as there are people who will tell you that squirrel makes a fine entree. You be the judge. This botch is strictly for people who sincerely feel that all the wiseguy chatter on "Mystery Science Theater 3000" gets in the way of some darned fine films. (SL)From Our Advertiser

"Battlefield: Earth" (2000, Roger Christian): Truly one of the most garish and tone-deaf films ever made, all the worse for having been adopted from an L. Ron Hubbard novel by people wishing to pay homage to his chowderheaded religion. Quentin Tarantino resurrected John Travolta's career, and when he meets up with St. Peter, he'll have to answer for this. (SL)

"Red Planet" (2000, Antony Hoffman): An expedition to Mars crashes and the survivors go batty, making this one of those movies with a plot that mirrors a little too closely what happened to the film itself. It was a rival project to "Mission to Mars" and came out later, which is why we rank it lower -- not only lousy but also slow on the draw. (SL)

"Mission to Mars" (2000, Brian De Palma): There's actually the spine of something good here, and some of it looks extraordinary. But the storytelling in this interplanetary spectacular gets more and more preposterous as it goes along, until it arrives at one of the goofiest finales the genre has ever seen. (SL)

"Armageddon" (1998, Michael Bay): No, it doesn't help any that Bruce Willis gets blown to bits at the end of it, or that Owen Wilson has a small, funny part. It's ugly, stupid and edited as if by a monkey on crack. And clear-thinking people are still nauseated by Ben Affleck's romancing of Liv Tyler with animal crackers five years after the fact. (SL)